qx100: 800lbs/inch spring sufficient?

[veloc_h]

My (original) kind shock is squeaking. Because it's only a spring, I'd like to replace it by a hydraulik oil/spring 125mm combination laying around. The spring says: 140N/mm which would correspond to 800 lbs/inch.
However the original kind shock says 1000 lbs/inch. I wonder whether or not it is too soft (my weight is 70kg).

 

[benphyr]

First, make sure the length of the shock from eye to eye 0-------0 is the same as the one being replaced. I think the QX100 has a 125mm shock.

Then check the length of travel of the each of the shocks.

If your replacement has longer travel you will be fine but if it has the same or less travel it may be too soft depending on how you set it up and how much of the travel you are currently using.

The amount that the shock is compressed at ideal sag is related to the force that is holding you up at ideal sag. (But different springs will have different compression curves): maximum support @ designated sag = spring force/unit length * length of travel. (You should use the same units of measure in order to compare. And only you can decide on the optimum sag of the shock.)

weight * length of travel
--------
inch

1000lbs/inch * length of stock spring = ?
800lbs/inch * length of oil shock = ?

If the support is similar then you should have no problems. Otherwise, you may want to check out the air shock that many have used available from Kind.

Either way, I would try it. Nothing to lose really. If it bottoms out too much tighten the spring up. If it still bottoms out then replace it. If it is too stiff, loosen the spring. If you can't then replace it.

 

[billyk]

I think all the older Qs had 125mm shocks. At least my Quest2-559 did.

But with the many many comments on this forum raving about the Kind air shocks, which are also pretty cheap, why consider anything else?

Proven durable, quite adjustable, stiffen the frame nicely, extremely light, ... What more could you ask for?

 

[benphyr]

I think all the older Qs had 125mm shocks. At least my Quest2-559 did.

I didn’t remember well. Shock size did not change until the Q45. Thank you for the correction. Updated above.

 

[veloc_h]

Actually the SU PA damper (similar to a DNM DV-22), given by friend) is lying around, the damping (tested withoud spring) works perfectly. Its finish is nice...

with the many many comments on this forum raving about the Kind air shocks, which are also pretty cheap, why consider anything else

Along with the restauration of a Challenge (Dutch) Taifun I wondered to buy one of these cheap Kind shocks a5rr1, but it says "friction" as damping type: http://exa-form.com/?products=a5-rr1. I was told by someone from the German recumbent forum, that one would loose quite some energie compared to better air dampers like the other Exa http://exa-form.com/?products=562r (which is not available in 125mm) and I was advised against the a5rr1.
As well I think the combination of hydraulic plus spring gives a better comfort.

The DNM reacts to small frequency imperfections where the kind shock is not as reactive.

. All in all I think for the Q series the a5rr1 125mm damper is an excellent alternative, which I might buy later (it's light and it seems to be robust). But for the present I want to swap the existing Kind shock 26 as soon as possible. It would take 4-6 weeks until I get the Exa from China. Hopefully the spring of the kind shock 26 has the same diameter and similar length as the other one. If so I could swap the spring.

Here the link to a comparison KS (now EXA) vs DNM DV-22: https://forum.cruzbike.com/threads/...ison-kind-air-shock-dual-v-dnm-22-coil.12758/

 

[jond]

Since that review which I stand by still I fitted DNM air shocks to both the hurricane and sofrider. Replacing the spring shocks in both cases. The air shocks offer a plush ride. Each shock type has pros and cons. Overall the advantage of the DNM air shock means they are keepers. I had zero luck with two kind air shocks. Others as noted love them. Cheap so get one.

 

[veloc_h]

I fitted DNM air shocks to both the hurricane and sofrider. Replacing the spring shocks in both cases.

For 125 only cheap air dampers from Exa and DNM are available (about the same price). Sofrider und Hurricane have 165mm, or am I wrong?

 

[jond]

For 125 only cheap air dampers from Exa and DNM are available (about the same price). Sofrider und Hurricane have 165mm, or am I wrong?

correct 165 mm both hurricane and sofrider. 38 mm travel. In practice around 20-25 mm normal operation. Sufficient for a plush ride. I’m 81 kg.

The construction of the 165 mm DNM and it’s utility for my application are were far better than the kind shock. Much less stiction with DNM despite weight disadvantages of DNM air shock. If you can afford to buy both. A 125 mm air shock is modest. In terms of travel. Therefore your bike deserves the best.

 

[veloc_h]

I wouldn't buy the dnm air 125mm (the friction class); bad feedback plus needle valve instead of schrader valve.
Would a 165mm damper for the qx100 damage the frame (forces in bad directions)?

 

[benphyr]

I wouldn't buy the dnm air 125mm (the friction class); bad feedback plus needle valve instead of schrader valve.
Would a 165mm damper for the qx100 damage the frame (forces in bad directions)?

Using a 165mm shock would push the rear down further and that would mean that it would steepen the head tube angle which would change the handling and handlebar flop. You also would get more forces on your fork and head tube. Elsewhere Cruzbike has recommended against changes that affect the head tube angle. If you set the pressure/spring slack enough that it results in the same geometry (sag) when loaded then you would have a shock that does not operate in full range but could function to get you home but it would likely bottom out frequently. It probably also depends somewhat on how heavy you and your gear are.

But basically, it was designed for 125mm so that is your best bet. The Kind one I have works fine and is a definite improvement over the stock coil at least by the time of replacement and for several years since.